Molybdenum is not found in nature as a free element, but rather, is predominantly found in the earth's crust in the form of molybdenite (MoS.sub.2). Perhaps the largest known source of molybdenite is at Climax, Colo., wherein the ore body comprises a highly silicified and altered granite, through which the molybdenite is distributed in the form of very fine-sized veinlets. Conventionally, the concentration of molybdenite in the ore as mined is in the order of 0.3 to 0.6 percent, which is increased through various beneficiation processes, such as an oil flotation extraction operation, to a concentration of molybdenum disulfide usually in excess of 80 percent by weight. Such oil flotation extraction operations conventionally employ pine oil and petroleum oil in combination with suitable wetting agents to effect a separation of the molybdenum disulfide constituent from the gangue which consists predominantly of silica.
In order to recover the metallic molybdenum constituent from the molybdenite concentrate, it has heretofore been common practice to subject the molybdenite concentrate to a roasting operation in the presence of air to convert the material to molybdenum trioxide, and the resultant oxidized concentrate is thereafter further purified by sublimation and in some instances, is still further purified by conversion of the molybdic oxide to ammonium molybdate. In the last stage, the purified molybdenum compound is reduced through a multiple-stage hydrogen reduction process to a relatively pure metallic state. It will be apparent that the foregoing processing sequence in accordance with prior art practices is costly and time consuming. Because of this, various alternative techniques have been proposed for producing metallic molybdenum including a direct thermal dissociation of molybdenite, but such prior art techniques have been unsatisfactory, particularly due to the low purity and/or high cost of the metallic molybdenum produced.
The present invention provides for a substantial simplification in the production of metallic molybdenum by a direct dissociation of the molybdenite into its component elements, enabling a recovery of sulfur and other normally-occurring contaminating elements as useable by-products and producing metallic molybdenum in a relatively pure form.